XPathExpression: evaluate() method
Baseline Widely available
This feature is well established and works across many devices and browser versions. It’s been available across browsers since July 2015.
The evaluate()
method of the
XPathExpression
interface executes an XPath expression on the given node or document and
returns an XPathResult
.
Syntax
evaluate(contextNode)
evaluate(contextNode, type)
evaluate(contextNode, type, result)
Parameters
contextNode
-
A
Node
representing the context to use for evaluating the expression. type
Optional-
Specifies the type of result to be returned by evaluating the expression. This must be one of the
XPathResult.Constants
. result
Optional-
Allows to specify a result object which may be reused and returned by this method. If this is specified as
null
or the implementation does not reuse the specified result, a new result object will be returned.
Return value
An XPathResult
object representing the result of evaluating the XPath
expression.
Exceptions
INVALID_EXPRESSION_ERR
If the expression is not legal according to the rules of the
XPathEvaluator
, an XPathException
of type
INVALID_EXPRESSION_ERR
is raised.
TYPE_ERR
In case result cannot be converted to the specified type, an
XPathException
of type TYPE_ERR
is raised.
NAMESPACE_ERR
If the expression contains namespace prefixes which cannot be resolved by the specified
XPathNSResolver
, a DOMException
of type
NAMESPACE_ERROR
is raised.
WRONG_DOCUMENT_ERR
If the provided context node is from a document that is not supported by the
XPathEvaluator
, a DOMException
of type
WRONG_DOCUMENT_ERR
is raised.
NOT_SUPPORTED_ERR
If the provided context node is not a type permitted as an XPath context node or the
request type is not permitted by the XPathEvaluator
, a
DOMException
of type NOT_SUPPORTED_ERR
is raised.
Examples
The following example shows the use of the evaluate()
method.
HTML
<div>XPath example</div>
<div>Number of <div>s: <output></output></div>
JavaScript
const xpath = "//div";
const evaluator = new XPathEvaluator();
const expression = evaluator.createExpression("//div");
const result = expression.evaluate(
document,
XPathResult.ORDERED_NODE_SNAPSHOT_TYPE,
);
document.querySelector("output").textContent = result.snapshotLength;
Result
Specifications
Specification |
---|
DOM Standard # dom-xpathexpression-evaluate |
Browser compatibility
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